Methods for shading materials for use in dental restorations are known. Ceramic materials in the form of powder and partially sintered bodies may be predictably colorized to achieve a shade of natural or matching dentition in a completed, fully sintered, dental restoration.
In one method, coloring agents in the form of colorized dipping solutions penetrate porous ceramic structures that are milled from bisque, or partially sintered, ceramics. After milling and dipping in coloring solutions, the colorized ceramic bodies are sintered to full density, achieving a targeted shade in the final dental restoration.
Ceramic material may be colorized prior to forming the material into millable ceramic blanks. For example, coloring agents may be added during ceramic processing steps, or via fluidized bed reaction of unshaded powders, or by blending pre-shaded ceramic powders. Colorized ceramic materials formed into shaded ceramic blanks may be milled as pre-sintered bodies, and then fully sintered to form a dental appliance in a variety of target shades.
Coloring solutions containing terbium and chromium are known for use in dental applications in which pre-sintered or bisque zirconia ceramic bodies shaped as dental restorations are soaked for penetration by the coloring solution. The combination of iron, erbium, and/or cobalt, for colorizing dental ceramic materials is known in dental applications as providing a desirable shade match to natural dentition in comparison to some alternative dental ceramic coloring components.
Sintered, shaded blanks may be useful for preparing chairside dental applications by eliminating the lengthy sintering step utilized with traditional restorative dentistry techniques. The ability to mill sintered blocks allows the dentist to scan, mill, and seat a crown within a few hours. The consolidation of multiple dental visits (required for traditional techniques) to a chairside process is beneficial to both the dentist and patient. However, color uniformity throughout a mass and/or volume of a millable, sintered ceramic body used in chairside applications may not be achievable for all shades utilizing iron, erbium, and/or cobalt shading systems.